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TH400 no downshift

Discussion in 'Chevy Trucks' started by Clemens, Jun 21, 2003.

  1. Clemens

    Clemens Junior Member
    from Europe
    Messages: 9

    Hey, on my 81 G30 ( I know this is a truck forum, but I feel mechanically it´s quite the same) i have a downshift problemwith the TH400

    Ever since I got the van 4 years ago it never downshifted while i was driving; i can downshift manually with the gear selector lever and it will upshift perfectly in ´D´, but there´s just no kickdown.

    I checked the downshift switch but it seems to work.

    Any idea what could be wrong with it? :confused:
     
  2. wyldman

    wyldman Member
    Messages: 3,265

    So when you checked the switch,It has continuity when the gas pedal is to the floor,and goes open when returned ?

    Have you got power to it,or through it to the trans ?

    It's a pretty simple circuit,and you seem to be on the right track.Trace your power\wiring all the way to the trans,and if it's OK,then it's internal.
     
  3. Clemens

    Clemens Junior Member
    from Europe
    Messages: 9

    that´s what im afraid it could be, something internal, but what specifically could it be? how does the tranny downshift?
     
  4. wyldman

    wyldman Member
    Messages: 3,265

    Inside the trans there is a detent solenoid,which could be defective.It could also be a number of other things,like shift lever adjustment,modulator valve,internal valve body problems,etc.